Preheat oven to 375 degrees F (190 degrees C).

Grease a large casserole dish.

In a medium mixing bowl, combine the Cheddar cheese soup, onions, and black pepper.

Slice the potatoes into 1/4 inch slices.

Arrange one layer of sliced potatoes in the bottom of the casserole dish.

Spoon one layer of the soup mixture over the potatoes.

Arrange another layer of potatoes and then more soup.

Continue layering until all of the ingredients have been used.

Sprinkle the shredded Cheddar cheese over the top of the casserole.

Bake until the cheese is bubbly and the potatoes are fully cooked, approximately 45 minutes.